This invention relates generally to a method for manufacturing a medical device. More particularly, the invention is directed to a method for manufacturing a medical device having a coated portion by laser ablation.
Implantable medical devices, such as prosthesis or stents, are used to reduce restenosis after balloon angioplasty or other procedures involving catheters. Usually, the suitable medical device or stent is cylindrical in shape. The walls of the cylindrical structure can be formed of metal or polymer with openings therein, e.g., a mesh. The stent is implanted into a body lumen, such as a blood vessel, where it stays permanently, to keep the vessel open and to improve blood flow to the heart muscle and relieve symptoms. Stents can also be positioned in other parts of the body, such as the kidneys or the brain. The stent procedure is fairly common, and various types of stents have been developed and actually used. However, since the bare metal surface of the stents may trigger restenosis, the stent surface should be altered to make it more biocompatible. Stents coated with polymers have been offered to reduce likelihood of restenosis caused by the metal surface of stents. Further, there are various types of polymer coats for stents which contain drugs which are delivered to an afflicted area of a body lumen. Drugs may be either bonded chemically, physically or absorbed in the polymer matrix. Also, for the purpose of obtaining drug delivery stents, the drugs may be directly coated or immobilized onto the stents, e.g. using a binding molecule between the drug molecule and the stent surface.
Previously, such coated stents have been manufactured by shaping the body of the stents first by photo-etching, laser ablation, electron beam ablation, or any other means, and then coating the stents with polymer compositions or drug compositions by dip-coating, spray-coating or any other means. However, due to the complex geometry of the stent, applying an even coating on a metal stent is very difficult. Therefore, methods for easily manufacturing a stent with uniform coating(s) are necessary.
In addition, the polymer coating, when applied by methods in the art, tends to create bridges at small gaps or corners between stent struts. Also, in the conventional methods, wherein a coating process takes place after a shaping process, it is almost impossible to selectively coat the stent. For example, it is impossible to coat one side of a stent without coating the other side or to apply different coatings to the outside and inside of a stent. Therefore, there is a need for methods of making a stent, especially coated stent, wherein the coating(s) does not form bridges at gaps or corners, and wherein selective coating of the stent can be readily achieved.
These and other objectives are accomplished by the present invention. To achieve the aforementioned objectives, a method has been invented for manufacturing a medical device having a coated portion by laser ablation.
An embodiment of the present invention is a method for manufacturing a medical device having a coated portion which comprises obtaining a structure having an inner surface and an outer surface. At least a portion of the inner or outer surface is coated with a first coating material. Then, the coated structure is ablated with a laser to form at least one opening therein to form the coated portion.
In another embodiment of the present invention, the method for manufacturing a medical device having a coated portion comprises obtaining a plate having a first surface and a second surface. At least a portion of the first surface or second surface is coated with a first coating material. The coated plate is then ablated with a laser to form at least one opening in the coated plate. Afterward, the coated and ablated plate is formed by folding or shaping into the medical device.